1. Field of the Invention
The subject invention relates to devices for the collection of analytical samples and, more particularly, devices used in collecting samples of a solvent or rinse agent that is exposed to the surface of an object.
2. Description of the Prior Art
In cleaning impermeable and semi-permeable materials, it is sometimes desirable or even necessary to identify or quantify a contaminant that may be present on the surface of the material. For example, in environmental clean-ups, such a determination is sometimes required to demonstrate that a surface has been adequately cleaned. As a specific example, in cleaning the surface of an object that is contaminated with polychlorinated biphenols ("PCBs"), it is sometimes necessary to demonstrate that the clean-up has achieved a standard that is expressed as an allowable mass of PCB's per unit area of surface.
In the prior art, such samples have sometimes been collected by wiping the material surface with a cloth or other absorbent material. In some instances, the absorbent material is also partially saturated with a rinsing agent or solvent of the contaminant. To demonstrate the amount of contaminant remaining on the surface of the object that is being cleaned, a portion of the cloth is analyzed according to a specified procedure. The amount of contaminant is then attributed to the area that was wiped with the cloth to determine the amount of contamination per unit area. However, this procedure is subject to several uncontrolled variables so that such samples are not always accepted as being representative of the degree of contamination present on the tested surface
As an alternative process, a rinsing agent or solvent is sometimes used to determine the degree of contamination that is present on the surface of an object The rinsing agent is exposed to the surface and a sample of the exposed rinsing agent is then analyzed to determine the concentration of contaminant in the rinsate. However, the results of this method are as much subject to the volume of rinsing agent that is used as they are to the amount of contaminant that is present. Moreover, various sample collection devices known in the prior art are not suited for collecting samples of a rinsing agent from the contaminated surface.
An example of such prior art devices is shown in U.S. Pat. No. 3,534,613 to Travor, et al. It describes a device for extracting a sample of the contents of an ordinance or other closed container. According to Travor, a sampling pin is located in a housing that is connected to a detonating assembly. When the detonating assembly is activated, the sampling pin pierces the container surface. The sampling pin is then used to withdraw a sample of the contents of the container. As another example, U.S. Pat. No. 3,521,715 to Kratein describes a device for the collection of soils or other permeable materials. A chemical grout is emitted from a probe when the probe is injected into the semi-permeable material. The grout is allowed to harden and captures a sample of the material when the probe is withdrawn.
Other prior art sample collection devices have merely relied on vacuum or suction techniques and are not suitable for use with a rinsing agent. For example, U.S. Pat. No. 4,088,025 to Foster, et al. and U.S. Pat. No. 3,748,905 to Fletcher, et al. ("Fletcher") describe sampling apparatus wherein vacuum suction is used to collect the sample. Fletcher concerns an apparatus intended to collect air-borne particles at a test surface. A vacuum source draws the particles from the test surface through a tip and a membrane filter housed in a cone assembly. The cone assembly can be inverted and disassembled by mechanical impact to access the filter However, there is no provision for applying a rinsing agent to the surface.
Other apparatus and methods also known in the prior art are subject to various other shortcomings and deficiencies. Thus, there was a need for an apparatus that could be used to expose an area of the surface of an object to a rinsing agent and to collect the rinsing agent for subsequent analysis In addition, there was a need for a device that would define the area of the surface to which the rinsing agent is exposed as well as quantify the amount of rinsing agent that is used.